Detailed quantification of glacier elevation and mass changes in South Georgia

Farías-Barahona, David; Sommer, Christian; Sauter, Tobias; Bannister, Daniel; Seehaus, Thorsten; Malz, Philipp; Casassa, Gino; Mayewski, Paul Andrew; Turton, Jenny; Braun, Matthias

doi:10.1088/1748-9326/ab6b32

Cited by 16 publications

(12 citation statements)

References 44 publications

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“…A crucial advantage of our approach is the combination of temporally consistent area and elevation measurements, which improve the accuracy of mass change estimates. Processing of elevation changes was adopted from previous studies [20][21][22][23] . A strength of the interferometric SAR compared with optical sensors is that radar acquisitions are not influenced by clouds or oversaturation by highly reflective surfaces (e.g., glacier accumulation areas).…”

Section: Resultsmentioning

confidence: 99%

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Rapid glacier retreat and downwasting throughout the European Alps in the early 21st century

et al. 2020

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Mountain glaciers are known to be strongly affected by global climate change. Here we compute temporally consistent changes in glacier area, surface elevation and ice mass over the entire European Alps between 2000 and 2014. We apply remote sensing techniques on an extensive database of optical and radar imagery covering 93% of the total Alpine glacier volume. Our results reveal rapid glacier retreat across the Alps (−39 km² a −1) with regionally variable ice thickness changes (−0.5 to −0.9 m a −1). The strongest downwasting is observed in the Swiss Glarus and Lepontine Alps with specific mass change rates up to −1.03 m.w.e. a −1. For the entire Alps a mass loss of 1.3 ± 0.2 Gt a −1 (2000-2014) is estimated. Compared to previous studies, our estimated mass changes are similar for the central Alps, but less negative for the lower mountain ranges. These observations provide important information for future research on various socioeconomic impacts like water resource management, risk assessments and tourism.

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Section: Resultsmentioning

confidence: 99%

“…Each TanDEM-X elevation model is processed by using differential SAR interferometry, according to the workflow described in previous studies [20][21][22][23] . Differential interferograms are calculated using the void-filled SRTM DEM as reference surface.…”

Section: Methodsmentioning

confidence: 99%

Rapid glacier retreat and downwasting throughout the European Alps in the early 21st century

et al. 2020

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“…For the 1955-2000 period, we discarded unrealistic positive values in the retreated part of the glacier present in the period 2000-2013. We removed strongly deviating values by applying a quantile filter (1%-99%) (e.g., [46]) and filled them in using the hypsometry function (e.g., [4]). Since the SRTM and TanDEM-X DEMs were acquired at the end of the austral summer (February-March), we converted the elevation changes to mass change using a density conversion factor of 850 ± 60 kg m −3 [47].…”

Section: Glacier Elevation and Mass Changesmentioning

confidence: 99%

60 Years of Glacier Elevation and Mass Changes in the Maipo River Basin, Central Andes of Chile

et al. 2020

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Glaciers in the central Andes of Chile are fundamental freshwater sources for ecosystems and communities. Overall, glaciers in this region have shown continuous recession and down-wasting, but long-term glacier mass balance studies providing precise estimates of these changes are scarce. Here, we present the first long-term (1955–2013/2015), region-specific glacier elevation and mass change estimates for the Maipo River Basin, from which the densely populated metropolitan region of Chile obtains most of its freshwater supply. We calculated glacier elevation and mass changes using historical topographic maps, Shuttle Radar Topography Mission (SRTM), TerraSAR-X add-on for Digital Elevation Measurements (TanDEM-X), and airborne Light Detection and Ranging (LiDAR) digital elevation models. The results indicated a mean regional glacier mass balance of −0.12 ± 0.06 m w.e.a−1, with a total mass loss of 2.43 ± 0.26 Gt for the Maipo River Basin between 1955–2013. The most negative glacier mass balance was the Olivares sub-basin, with a mean value of −0.29 ± 0.07 m w.e.a−1. We observed spatially heterogeneous glacier elevation and mass changes between 1955 and 2000, and more negative values between 2000 and 2013, with an acceleration in ice thinning rates starting in 2010, which coincides with the severe drought. Our results provide key information to improve glaciological and hydrological projections in a region where water resources are under pressure.

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“…A common, but unproven, assumption to account for the uncertainty due to void filling in elevation change fields is to apply a multiple ( f V of 2 to 5) of the error of the measured elevation changes δ dh , typically estimated on ice-free areas, to the void areas [2,4,5,7,20,29,30]. The subsequent volume change uncertainty on the void-filled region is computed as…”

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confidence: 99%

Novel Techniques for Void Filling in Glacier Elevation Change Data Sets

et al. 2020

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The increasing availability of digital elevation models (DEMs) facilitates the monitoring of glacier mass balances on local and regional scales. Geodetic glacier mass balances are obtained by differentiating DEMs. However, these computations are usually affected by voids in the derived elevation change data sets. Different approaches, using spatial statistics or interpolation techniques, were developed to account for these voids in glacier mass balance estimations. In this study, we apply novel void filling techniques, which are typically used for the reconstruction and retouche of images and photos, for the first time on elevation change maps. We selected 6210 km2 of glacier area in southeast Alaska, USA, covered by two void-free DEMs as the study site to test different inpainting methods. Different artificially voided setups were generated using manually defined voids and a correlation mask based on stereoscopic processing of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) acquisition. Three “novel” (Telea, Navier–Stokes and shearlet) as well as three “classical” (bilinear interpolation, local and global hypsometric methods) void filling approaches for glacier elevation data sets were implemented and evaluated. The hypsometric approaches showed, in general, the worst performance, leading to high average and local offsets. Telea and Navier–Stokes void filling showed an overall stable and reasonable quality. The best results are obtained for shearlet and bilinear void filling, if certain criteria are met. Considering also computational costs and feasibility, we recommend using the bilinear void filling method in glacier volume change analyses. Moreover, we propose and validate a formula to estimate the uncertainties caused by void filling in glacier volume change computations. The formula is transferable to other study sites, where no ground truth data on the void areas exist, and leads to higher accuracy of the error estimates on void-filled areas. In the spirit of reproducible research, we publish a software repository with the implementation of the novel void filling algorithms and the code reproducing the statistical analysis of the data, along with the data sets themselves.

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Detailed quantification of glacier elevation and mass changes in South Georgia

Cited by 16 publications

References 44 publications

Rapid glacier retreat and downwasting throughout the European Alps in the early 21st century

Rapid glacier retreat and downwasting throughout the European Alps in the early 21st century

60 Years of Glacier Elevation and Mass Changes in the Maipo River Basin, Central Andes of Chile

Novel Techniques for Void Filling in Glacier Elevation Change Data Sets

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